Distances can be measured using standard measuring contraptions such as yardsticks, rulers, and so on. These devices generally measure linear distances representing a distance between a first point and a second point in Euclidean space (e.g., in a plane) along a straight line. The linear distances are considered to be the shortest distances between two points, and have generally been used since antiquity.
Other techniques have been in existence for some time include flexible tape measures and wheel-based rolling measures that allow the distance along a non-linear (e.g., curved) path to be measured. These things are useful for measuring a circumference of a curved surface or the distance along a winding perimeter, path, and so on.
Generally speaking, all of the above measuring devices require the user carrying out the measurement to physically position the devices, or ends thereof at two or more locations along the object being measured. For example, to measure the length of an object with a ruler, a person holds the ruler against the object and reads off the measurement increments to obtain the length reading. And to use a flexible tape measure, the user holds the tape against the surface being measured and reads off the units of measurement.
These devices above are not conducive to measuring the length of an object in an inaccessible location. For example, if a person standing on the ground wishes to measure the length of a beam along an elevated ceiling of a building, the person would typically climb up to the ceiling on a ladder to place a ruler or tape measure against the beam to measure its length. This can be inconvenient, dangerous, or not possible.
Some distance measurement devices have been developed recently that do not require physical contact or proximal placement against the objects being measured. For example, commercially available “laser distance measuring” devices or “laser range finder” products can be used from a position remote to the object being measured. These products deliver a beam of laser light, which is projected out from a hand-held apparatus, impinging upon the object whose distance is to be measured, and displaying to the user a distance from the apparatus to the object upon which the laser light is being shone.
In some cases, existing systems require measurements to be conducted from a reference point situated in-line with a side of an object of interest or in the plane of the object of interest, and so they are not convenient. Also, being able to deliver a beam from a measurement apparatus to a point of interest lying in a plane of a solid object is not practical and grazes the object at an extremely shallow angle (theoretically a zero degree angle of incidence on the face of the object) so that receiving a meaningfully measurable return scattered signal is difficult or impossible or forces the user to actually depart from the actual plane of the object—thereby reducing the accuracy of the measurement being made.
It has not been possible or practical so far to make measurements that a user can conduct at a distance from the object being measured conveniently and accurately, especially if the measurements are along irregular or non-linear paths, it also has been impossible or impractical to measure such lengths, areas, and volumes of objects from a location that is not proximal to or in-plane with the object being measured.